giles
609205b551
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Test, Build, and Deploy / test-build-deploy (push) Failing after 22s
Linear-time stack algorithm for largest rectangle in histogram:
for i = 0 to n do
let h = if i = n then 0 else heights.(i) in
while top-of-stack's height > h do
pop the top, compute its max-width rectangle:
width = (no-stack ? i : i - prev_top - 1)
area = height * width
update best
done;
if i < n then push i
done
Sentinel pass at i=n with h=0 flushes the remaining stack.
For [2; 1; 5; 6; 2; 3], bars at indices 2 (h=5) and 3 (h=6) form
a width-2 rectangle of height 5 = 10.
Tests guarded patterns with `when` inside while-cont-flag, nested
`match !stack with | [] -> i | t :: _ -> i - t - 1` for width
computation.
178 baseline programs total.
28 lines
657 B
OCaml
28 lines
657 B
OCaml
let max_rect heights =
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let n = Array.length heights in
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let stack = ref [] in
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let best = ref 0 in
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for i = 0 to n do
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let h = if i = n then 0 else heights.(i) in
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let cont = ref true in
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while !cont do
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match !stack with
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| top :: rest when heights.(top) > h ->
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let height = heights.(top) in
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stack := rest;
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let width = match !stack with
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| [] -> i
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| t :: _ -> i - t - 1
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in
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let area = height * width in
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if area > !best then best := area
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| _ -> cont := false
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done;
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if i < n then stack := i :: !stack
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done;
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!best
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;;
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max_rect [| 2; 1; 5; 6; 2; 3 |]
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